Web Page 7 of 8

Summary of Current Information
 A. The Parent Star B. The Exoplanet

### VI. Calculating the Probability of Finding this Exoplanet

Even if a star has an orbiting planet, only in a very small percentage of cases will that planet make a transit across the disk of the star as seen from Earth's perspective.

The probability for a planet with a circular orbit is given by:

 probability (%) = (Rstar / a) * 100%
 % = ( (Press the calculate button to estimate the mass of the exoplanet.)

where

• Rstar is the radius of the parent star in AU. (Dividing by 215 converts solar radii to AU.)
• a is the average distance the planet is from the star, i.e., the semi-major axis of the planet's orbit about the star, in AU.

Press the button for a summary of your analysis.

### Explanations

Notes on Computing the Probability of Finding the Exoplanet

A complete derivation of the probability of finding a given exoplanet assuming a uniform random distribution of the angle that the plane of its orbit makes with respect to our line of sight to the star is gven by the formula above.

Hints (Reminders)

• Use the appropriate buttons. Do not press the "Enter" key.
• Enter or change numbers only in the appropriate boxes.
• Complete all "calculations" in order from the top of the page to the bottom.